Photoelectrochemical secondary cell and battery

Abstract

A photoelectrochemical secondary cell comprising a photocatalytic anode, or photoanode; an anode; a cathode comprising a metal hydride; electrolyte; separator; and case at least a portion of which is transparent to the electromagnetic radiation required by said photoanode to charge said photoelectrochemical secondary cell.

1 . A photoelectrochemical secondary cell comprising:
 a case;   a photocatalytic anode or photoanode electrode disposed within the case;   an anode electrode disposed within the case;   a negative electrode comprising substantially a metal hydride disposed within the case;   said photocatalytic anode or photoanode electrode and anode electrode being disposed on opposite sides of a base with said anode electrode facing said negative electrode;   a gas separator disposed in the case between said anode electrode and said negative electrode and attached to the inside of the case to form two separate chambers; and   an electrolyte disposed in both the chambers, the electrolyte being capable of being reduced to hydrogen at the negative electrode;   at least a portion of the case being transparent to electromagnetic radiation required by said photocatalytic anode or photoanode electrode to charge said photoelectrochemical secondary cell.   
     
     
         2 . The photoelectrochemical secondary cell of  claim 1  wherein the base provides separate electrical connections to the anode electrode and to the photocatalytic anode or photoanode electrode. 
     
     
         3 . The photoelectrochemical secondary cell of  claim 1  wherein the base provides a common electrical connection to the anode electrode and to the photocatalytic anode or photoanode electrode. 
     
     
         4 . The photoelectrochemical secondary cell according to  claim 1  wherein said photocatalytic anode or photoanode electrode comprises one or more of the following: titania that is dyed; titania that is doped; strontium titanate; compounds and alloys of titania and titanium with tungsten, tungsten oxide, cadmium sulfide, iron, oxides of iron, or silicon; silicon seeded with nickel surface particles; nanotubes of titanium dioxide; carbon nanotubes further comprising semiconductor materials; graphene; quantum dots; photonic bandgap crystals; strained semiconductor; and strained titania. 
     
     
         5 . The photoelectrochemical secondary cell according to  claim 1  wherein said photocatalytic anode or photoanode electrode and said anode electrode are provided with louvers or other apertures. 
     
     
         6 . The photoelectrochemical secondary cell according to  claim 1  wherein said anode electrode comprises at least one or more of: nickel hydroxide on nickel; mixed metal oxides of ruthenium, titanium and iridium on titanium; plated nickel or nickel hydroxide film on titanium; and nickel or nickel hydroxide particles on titanium; and wherein said titanium is a rod, plate, sheet, foil, or expanded mesh. 
     
     
         7 . The photoelectrochemical secondary cell according to  claim 1  wherein said anode electrode is formed by at least one or more of:
 applying a paste; sintering; calcification; thermal oxidation; anodizing; alloying; plating; powder coating; mechanical compression; casting; vacuum deposition; or chemical vapor deposition. 
 
     
     
         8 . The photoelectrochemical secondary cell according to  claim 1  wherein said gas separator comprises a non-woven felt of at least one or more of: polyolefin; polyethylene; or polypropylene. 
     
     
         9 . The photoelectrochemical secondary cell according to  claim 1  wherein said negative electrode comprises metal hydride in electrical contact with a nickel foam ribbon. 
     
     
         10 . The photoelectrochemical secondary cell according to  claim 1  wherein said metal hydride comprises a metal alloy of one or more of elemental forms: AB; AB2; AB5; or AB5-B. 
     
     
         11 . The photoelectrochemical secondary cell according to  claim 1  wherein said portion of said case transparent to electromagnetic radiation comprises at least one of ultraviolet-transmitting (UVT) acrylic or borosilicate 3.3 glass. 
     
     
         12 . The photoelectrochemical secondary cell according to  claim 1  wherein said electrolyte comprises at least one of potassium hydroxide or potassium carbonate. 
     
     
         13 . The photoelectrochemical secondary cell according to  claim 12  wherein said electrolyte further comprises one or more of the following additives: co-electrolytes, additives for improved high or low temperature performance, or for viscosity or polymerization for leak containment, methanol; thickeners; co-electrolytes; or refractive index matching additives, or for more efficient gas evolution. 
     
     
         14 . The photoelectrochemical secondary cell according to  claim 1  wherein said transparent portion of said case is cylindrical, being either convex or concave. 
     
     
         15 . A photoelectrochemical secondary battery comprising a plurality of photoelectrochemical secondary cells according to  claim 1 . 
     
     
         16 . The photoelectrochemical secondary battery according to  claim 15  wherein said photoelectrochemical secondary cells are connected electrically in at least one of series or in parallel. 
     
     
         17 . A photoelectrochemical secondary battery comprising a plurality of photoelectrochemical secondary cells according to  claim 1  or  2  stacked in a common case, with space and means between each of said cells to facilitate guiding of external light to the photoanodes within each of said cells, a portion of said case having a receiving window hat is transparent to the electromagnetic radiation required by said photoanodes to charge said secondary battery. 
     
     
         18 . The photoelectrochemical secondary battery according to  claim 17  wherein said means of guiding of external light to said photoanodes can facilitate light guiding processes including one or more of light scattering, waveguiding, light-piping, diffraction, refraction, and or reflection, and further where said means of guiding includes the gas separator material above said photoanode and/or by specialized separate optical surface or surfaces, including holographic optical surface or surfaces. 
     
     
         19 . The photoelectrochemical secondary battery according to  claim 18  wherein said receiving window is placed at the focus of a light concentrator. 
     
     
         20 . The photoelectrochemical secondary battery according to  claim 17  further comprising charge control means to manage charge modality by averting electrical shorting, said charge control means comprising an external charging management circuit which connects the photocatalytic anode or photoanode electrode to the cathode for charging, and disconnects the photocatalytic anode or photoanode electrode from the cathode upon full charge and for discharge. 
     
     
         21 . The photoelectrochemical secondary battery according to  claim 17  wherein said plurality of photoelectrochemical secondary cells are adjacent and coplanar. 
     
     
         22 . A method of storing hydrogen by photochemically and/or electrochemically charging a metal hydride, the method comprising:
 providing a photoelectrochemical secondary battery comprising a photocatalytic anode or photoanode electrode, an anode electrode, a negative electrode comprising substantially a metal hydride, and an encased electrolyte capable of being reduced to hydrogen at the negative electrode, the photocatalytic anode or photoanode electrode, the anode electrode and the negative electrode, all being immersed in the electrolyte;   exposing the photocatalytic anode or photoanode electrode to radiation while applying zero bias voltage potential, or a bias voltage potential that is lower than the theoretical water splitting voltage of 1.48 VDC between said photocatalytic anode or photoanode electrode and said negative electrode,   and/or applying a voltage potential of at least 1.48 VDC between said anode electrode and said negative electrode,   
       thereby charging said metal hydride with hydrogen.